Weldless rebar chairs

ABSTRACT

A form for creating a weldless rebar chair has an elongate rod arranged along a predetermined direction, said rod being formed into at least a plurality of partial elongate loops spaced from each other along the predetermined direction and arranged in a common plane defined by the elongate rod and the elongate loops. A method of producing a weldless rebar chair comprising the steps of arranging an elongate rod along the predetermined direction and bending it to create the elongate loops spaced and bending the loops at transition points to form intermediate portions arranged in a common plane and free ends that extend in directions normal to the plane, alternate free ends being bent in opposite directions and having lengths that are substantially equal to provide legs that can be placed on a surface to stabilize the rebar chairs.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to reinforcement bar supports in theconstruction trades and, more specifically, to weldless rebar chairs.

2. Description of the Prior Art

Rebar spacers or chairs are devices that support and securereinforcement steel bars or “rebars” in reinforced concrete structuresas the rebars are assembled in place prior to the final pouring of theconcrete. The spacers are left in place for the pour to keep them inplace to become a permanent part of the structure.

Rebar spacers or chairs can generally be divided into three raw materialcategories: concrete spacers, plastic spacers and metal spacers. Whileplastic spacers generally have the advantage of being low cost and fastprocessing, plastic spacers or bar supports or “chairs” cannot bond wellwith concrete. They are not compatible materials. Also, plastic has acoefficient of thermal expansion and contraction that is approximately10-15 times that of concrete. When subjected to temperature variationsthe plastic continues to expand and contract at that higher coefficient.Also, at high temperatures, plastic can even melt resulting inseparation between the spacers and the poured concrete, creating freepassages for corrosive elements to reach the steel reinforcements fromthe exterior of the concrete product. This frequently causes the steel,and eventually the concrete, to corrode. Concrete spacers are clearlymade of the same material as the poured concrete, so thermal expansionand contraction are the same. Because they are the same material, theconcrete spacers will bond with no gaps. Concrete spacers and barsupports help maintain the material integrity and uniformity of theconcrete and provide a cover over the reinforcement that protectsagainst corrosion. However, concrete spacers or chairs are impracticalin some respects. They are heavy, tend to be brittle and crack prior touse and must be preformed for each size or height of chair required.Since chairs can be specified in increments of approximately one-halfinch, this may result in a massive inventory problem that requires muchspace and expense. Many rebar spacers or chairs have been formed ofsteel. Examples of the different types of chair configurations aredisclosed, for example, in a “Bar Support Handbook” published by DaytonSuperior that lists the various types of metal, plastic and cementitioussupports and their various properties. However, each of these categoriesmust be formed in all the different sizes or heights that can bespecified so all entail significant inventory problems.

While steel rebar chairs have proven to be very popular bar supports arefrequently classified in terms of methods employed to minimize rustspots or similar blemishes on the surface of the concrete directlycaused by the bar support. Thus, for example, one type of rebar chair iscoated with plastic or is plastic protected. These provide protectionintended for use in situations of moderate to severe exposure. Maximumprotection is provided with epoxy-coated reinforcement bars. Bars thatare vinyl-coated or plastic-coated are intended for use in situations ofmoderate to maximum exposure. They are generally used when epoxy-coatedreinforcement bars are required. Steel and stainless steel chairs areused for moderate protection intended in situations of moderate exposurewhere the risk of rust needs to be taken into account. However, in athird category of chairs or spacers, no protection is provided againstrusting. In selecting one of the chairs including plastic feet, epoxycoated or plastic tipped feet or stainless steel tips; the cost ofproduction is always a factor.

Most of the steel chairs or spacers require some degree of welding tosecure the chairs or rebar supporting members to the legs that areconfigured to provide the desired height(s) for positioning thesupported rebars above the ground or other support surface. Despite thenumerous finishes applied to steel spacers or supports a problem thathas persisted is that many of the steel spacers or chairs typically rustwithin a matter of five to ten years. Therefore, there has existed ademand for a rebar chair or spacer that has a much longer lifetimewithout corroding. However, rebar steel that has resisted corrosion hasalso resisted being welded and, as indicated, steel spacers or chairshave traditionally required welding. These two desired properties havenot been amenable to using corrosion-resistant steels such as the ChromX9000 Series of steels marketed by MMFX Technology Corp. of Irvine,Calif.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide rebar spacersor chairs that do not have the disadvantages inherent prior art steelproducts of this type.

It is another object of the invention to provide rebars spacers orchairs that are simple in construction and economical to manufacture.

It is still another object of the invention to provide rebar spacers orchairs as in the previous objects that use ultra high strengthcorrosion-resistant steel that, at the same time, exhibits very goodductility and, therefore, can be bent into desired shapes.

It is yet another object of the invention to provide rebar spacers orchairs of the type under discussion that uses high strength corrosionresistant steel, despite being resistant to welding, that can be easilyand inexpensively shaped to provide the desired spacer or chairconfigurations without welding.

It is a further object of the invention to provide rebar spacers orchairs as in the previous objects that can be formed on the fly as maybe required in any given application to thereby avoid the need to stocklarge inventories of spacers or chairs in many incremental sizes orheights.

It is still a further object of the invention to provide rebar chairs orspacers as aforementioned that can use corrosion-resistant steel, suchas the MMFX 9000 Series reinforcing steels that exhibit high strengthand rebar corrosion resistance without the need for any welding to formspacers or chairs so that they are weldless and can be easily or readilycustomized to any given application.

It is yet a further object of the invention to provide rebar chairs orspacers that are weldless and can be formed by bending with inexpensiveconventional steel rod bending machinery.

A weldless rebar chair can be produced by using an elongate rod of highstrength, ductile and corrosion-resistant steel formed with elongateloops each provided with free ends and intermediate portions between thefree ends and the elongate rod. The intermediate portions are arrangedin a common plane defined by the elongate rod and the intermediateportions and the free ends are bent out of the common plane indirections generally normal to the intermediate portions. Alternate freeends are bent in opposite orthogonal directions in relation to thecommon plane. The intermediate portions of the loops have lengths withinthe common plane that are substantially equal to provide legs that canbe placed on a surface to stabilize the rebar chair. The method ofproducing the aforementioned form and weldless rebar chair are alsodisclosed and form part of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Those skilled in the art will appreciate the improvements and advantagesthat derive from the present invention upon reading the followingdetailed description, claims, and drawings, in which:

FIG. 1 is a side elevational view of a form for creating a weldlessrebar spacer or chair that includes a plurality spaced closed loops thatproject within a common plane in a direction away from the rod;

FIG. 2 is a side elevational view of a form for creating a weldlessrebar spacer or chair that includes a plurality spaced open loops thatproject within a common plane in a direction away from the rod;

FIG. 3 is a side elevational view of a rebar spacer or chair formed fromthe form shown in FIG. 1;

FIG. 4 is a top plan view of the rebar spacer or chair shown in FIG. 3;

FIG. 5 is similar to FIG. 3 but showing a rebar spacer or chair madewith the form shown in FIG. 2;

FIG. 6 is a top plan view of the rebar spacer or chair shown in FIG. 5;

FIG. 7 is a perspective view of three different spacers or chairscreated from the open loop form shown in FIG. 2 wherein the intermediateportions are varied to change the heights of the rebar-supporting rods;

FIG. 8 is a perspective view showing two different height rebar spacersor chairs of the type shown in FIG. 7 for supporting reinforcing bars orrebars at two different heights or levels prior to pouring of concrete;

FIG. 9 is a top plan view of the spacers or chairs and attached rebarsas shown in FIG. 8;

FIG. 10 is an end elevational view of an alternate configuration of arebar chair; and

FIG. 11 is similar to FIG. 10 showing a modified form of the alternateconfiguration that raises the height of the chair for rebars.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now specifically to the Figures, in which identical or similarparts are designated by the same reference numerals throughout, andfirst referring to FIG. 1, a form for producing rebar spacers or chairsis designated by the reference numeral 10 comprises an elongate rod 12that defines a predetermined direction, along axis A, the rod beingformed with a plurality of at least partial elongate loops 14, generallyuniformly spaced from each other as shown along the axis A. The rod 12and the elongate loops 14 define a common plane (the plane of FIG. 1).The loops 14 in the form 10 are generally closed loops as shown. In theillustrated configuration the loops are spaced a distance S along theaxis A. The widths of the individual loops 14 are designated by thedimension s although neither the dimensions S nor s is critical for thepurposes of the present invention. These may be selected to meetspecific requirements on a particular project, conform to required costloads.

Further described in connection with FIGS. 3 and 4 the form 10 can beformed into rebar chairs or spacers by only using bending equipment.This requires that the bar or rod 12 is not only sufficiently strong tosupport the rebars but also must be ductile to allow bending ordeformation of the steel to create the loops without undue effort orcost. This has been difficult if not impossible to do with stainlesssteel or other steels that are generally corrosion resistant. ChromX9000 Series steels marketed by MMFX Technology Corp., of Irvine Calif.is an ideal material for use in connection with the rebar spacers orchairs in accordance with the invention. The use of ChromX 9000 Seriessteels, including 9100 (ASTM A1035 CS Grade 100 Steel) and 9120 (ASTMA1035 CS Grade 120 Steel) steels, with the subject invention saveconstruction time and labor. The product's corrosion protection extendsthe service life and reduces the life cycle cost for concrete structureseven in highly corrosive environments. Its uncoated corrosion protectionmeans no additional costs from special handling, coating, inspection andrepair. The aforementioned MMFX steels are more fully disclosed in U.S.Pat. No. 4,671,827 issued on Jun. 9, 1987 to Thomas et al., for Methodof Forming High-Strength, Tough, Corrosion-Resistant Steel. Additionalpatents that have been issued relating to MMFX Steel that describes suchcorrosion resistance steel products include: U.S. Pat. Nos. 4,170,499;4,619,714; 6,273,968; 6,709,534; 7,118,637; 6,746,548; 6,827,797; and7,214,27.

The rod 12 can be bent by conventional machinery. The rods can be formedas shown in FIG. 1 either in predetermined or fixed lengths or becontinuous. Referring to FIG. 3 and 4, the advantages of the weldlessmethod of creating rebar spacers or chairs will become immediatelyappreciated. The closed loops 14 shown in FIG. 1 have free ends 14 a andintermediate portions 14 b between the free ends 14 a and the elongatesteel rod 12. The intermediate portions 14 b are arranged in a commonplane, in the plane of the drawing, with the elongate rod 12 and theintermediate portion and the free ends 14 a being bent out of the commonplane in a direction generally normal to the intermediate portions. Inorder to form the spacers or chairs alternate free ends 14 a are bent inopposite orthogonal directions in relation to the common plane. Theintermediate portions 14 b have lengths within the common plane whichare substantially equal to provide legs 22 that can be placed on asurface to stabilize the rebar spacers or chairs.

The specific configurations of the loops that are formed from the rod 12are not critical. What is important is that the loops extend from therod along a direction A_(T) so that the loops can define a transitionpoint 14 c that separates the free ends 14 a and the intermediateportions 14 b. In FIGS. 1, 3 and 4 the loops are shown to be closedloops. In FIGS. 2, 5 and 6 the loops are shown as open loops 16. Eitherone can be used with different degrees of advantage. In bothconfigurations, the loops extend along a transverse direction A_(T) tothe axis A and have a total length L. The free ends have a length mwhile the intermediate portions have a length equal to l so that L=l+m.In forming a spacer or chair from either one of the forms shown in FIGS.1 and 2, the loops 14, 16 are bent at the transition points 14 c , 16 crespectively to form intermediate portions 14 b, 16 b arranged in thecommon plane defined by the elongate rods 12 and the intermediateportions while the free ends 14 a, 16 a respectively extend out of thecommon plane in directions generally normal to the intermediate portionsas shown. Alternate free ends are bent in opposite orthogonal directionsin relation to the common plane so that the intermediate portions havesubstantially equal lengths l within the common plane to providesimilarly dimensioned legs 22 that can be placed on a surface tostabilize the rebar space or chair.

Referring to FIG. 7, three different configurations 20, 20′, 20″ of theopen loop rebar spacer or chair of the type shown in FIGS. 2, 5 and 6are shown. Each of these was initially formed from the same open loopform 10′ each having loops with the same longitunal length L. The spaceror chair 20 was formed by bending the open loop 16 to provide anintermediate portion 16 b that generally raises the height of the rod 12above the support surface at the same time generally decreasing thelength of the free end 16 a. The intermediate spacer or chair 20′ shownin FIG. 7 is formed to lower the height of the rod 12 by decreasing theheight of the intermediate portion 16 b′, thereby increasing the lengthof the free end 16 a′. As indicated, the total lengths the free ends andthe intermediate portions will be equal to the initial overall length Lof the loops. Similarly, the spacer or chair 20″ is similar to the otherchairs 20, 20′ except that now the rod 12 has been lowered still furtherby decreasing the dimension of 16 b″ while, as before, the length of thefree end 16 a″ increases. Clearly, the lengths of the free ends 16 a, 16a′ and 16 a″ is not critical and can be any dimension. The only criticaldimension is the heights of the intermediate portions which can becustomized to accommodate any given height requirement withoutconsidering the otherwise needed dimensions or heights. Referring toFIGS. 8 and 9, there is illustrated the means for supporting two levelsof reinforcement bars or rebars at two different heights, using thelowest height spacer or chair 20 shown in FIG. 7 and the higher heightspacer or chair 20″. The lower rebars are designated by the referencenumeral 24 while the higher rebars are designated by the referencenumeral 26. Transverse rebars 28 can also be secured to the rebars 24,26 that rest directly on the spacers or chairs. Conventional ties 30 canbe used to secure the rebars to each other or rebars to the chairs orspacers as shown.

It will be appreciated that the present invention provides tremendousflexibility in the construction trades. Not only is the product superiorand can last over a hundred years without corrosion the inventoryproblem is virtually eliminated or significantly reduced. Whether theloops are closed, open or otherwise a steel of the type under discussionthat can be readily bent to provide the desired heights of the spacersor chairs can be made in whatever heights are needed from the same formsby making the dimension L sufficiently large to allow the formation ofrebar spacers or chairs with legs determined by the desired or requireddimension l. These can provide the full gamut of heights that may beneeded at a construction site.

While the presently preferred embodiments utilize MMFX steels asaforementioned, other steels that have similar properties can also beused, namely high strength, good ductility and corrosion resistantsteels. Preferably, the steel should be corrosion resistant for at leastone hundred years. Thus, while the initial cost of both the steel andproduction might be higher than the use of conventional steels suchhigher initial cost is offset by the extended corrosion resistance sothat over the long term the effective costs of installation,construction and repair will be reduced.

FIGS. 10 and 11 illustrate alternate configurations 32 of a rebar chairthat can use the forms 10 or 10′. However, instead of bending the loops14, 16 at transition points 14 c. 16 c to modify the heights of thechairs alternate loops 14, 16 are angularly offset about the axis A ofthe rod 12. In. FIG. 10 alternate loops are offset angles θ₁ and θ₂ inrelation to a vertical plane extending through the axis A of rod 12 toelevate the rod 12 a height h₁. While angles θ₁, θ₂ do not need to beidentical they are preferably equal or substantially equal. When theheight of the chair needs to be increased the loops can be deflected orangularly offset by smaller angles θ₃, θ₄ to increase the chair heightto h₂. Again the angles θ₃, θ₄ are preferably equal or substantially thesame.

All of the embodiments provide a wide range of height adjustability byeither shifting the locations of the transition points 14 c, 16 c alongthe lengths L of the loops 14, 16 or by changing the angles θ₁-θ₄.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

What is claimed:
 1. A form for creating a weld-less rebar chaircomprising a continuous elongate rod arranged along a predetermineddirection, said rod being formed into at least a plurality of loopsextending substantially equal distances in a common direction normal tosaid predetermined direction spaced from each other along saidpredetermined direction and arranged in a common plane defined by saidelongate rod and said elongate loops.
 2. A form as defined in claim 1,wherein said loops are elongate loops.
 3. A form as defined in claim 1,wherein said loops are open loops.
 4. A form as defined in claim 1,wherein said loops are closed loops.
 5. A form as defined in claim 1,wherein said elongate rod is made of ASTM A1035 CS Grade 100 steel.
 6. Aform as defined in claim 1, wherein said elongate rod is made of ASTMA1035 CS Grade 120 steel.
 7. A form as defined in claim 1, wherein saidelongate rod is made of steel that achieves yield strength between 100and 120 Ksi of the ASTM A1035 specification while maintaining ductilityand tensile-to-yield ratio above 1.25.
 8. A weld-less rebar chaircomprising an elongate rod arranged along a predetermined direction,said rod being formed into at least a plurality of loops extendingsubstantially equal distances in a common direction normal to saidpredetermined direction spaced from each other along said predetermineddirection, said loops having free ends and intermediate portions betweensaid free ends and said elongate rod, said intermediate portions beingarranged in a common plane defined by said elongate rod and saidintermediate portions and said free ends being bent out of said commonplane in directions generally normal to said intermediate portions,alternate free ends being bent in opposite orthogonal directions inrelation to said common plane, said intermediate portions having lengthswithin said common plane that are substantially equal to provide legsthat can be placed on a surface to stabilize the rebar chair.
 9. Aweld-less rebar chair as defined in claim 8, wherein said loops areelongate loops.
 10. A weld-less rebar chair as defined in claim 8,wherein said loops are open loops.
 11. A weld-less rebar chair asdefined in claim 8, wherein said loops are closed loops.
 12. A weld-lessrebar chair as defined in claim 8, wherein said elongate rod is made ofASTM A1035 CS Grade 100 steel.
 13. A weld-less rebar chair as defined inclaim 8, wherein said elongate rod is made of ASTM A1035 CS Grade 120steel.
 14. A weld-less rebar chair as defined in claim 8, wherein saidelongate rod is made of steel that achieves yield strength between 100and 120 Ksi of the ASTM A1035 specification while maintaining ductilityand tensile-to-yield ratio above 1.25.
 15. A method of producing a formfor creating a weld-less rebar chair comprising the steps of selecting alength of an elongate continuous rod and arranging it along apredetermined direction; bending said rod to create a plurality of loopsextending substantially equal distances in a common direction normal tosaid predetermined direction spaced from each other along saidpredetermined direction in a common plane defined by said elongate rodand said elongate loops.
 16. A method as defined in claim 15, whereinsaid loops are open loops.
 17. A method as defined in claim 15, whereinsaid loops are closed loops.
 18. A method as defined in claim 15,wherein said elongate rod is made of ASTM A1035 CS Grade 100 steel. 19.A method as defined in claim 15, wherein said elongate rod is made ofASTM A1035 CS Grade 120 steel.
 20. A method as defined in claim 15,wherein said elongate rod is made of steel that achieves yield strengthbetween 100 and 120 Ksi of the ASTM A1035 specification whilemaintaining ductility and tensile-to-yield ratio above 1.25.
 21. Amethod of producing a weld-less rebar chair comprising the steps ofselecting a length of an elongate continuous rod and arranging it alonga predetermined direction; bending said rod to create at least aplurality of loops extending substantially equal distances in a commondirection normal to said predetermined direction spaced from each otheralong said predetermined direction, bending said loops at transitionpoints to form intermediate portions arranged in a common plane definedby said elongate rod and said intermediate portions and free ends thatextend out of said common plane in directions generally normal to saidintermediate portions, alternate free ends being bent in oppositeorthogonal directions in relation to said common plane, saidintermediate portions having lengths within said common plane that aresubstantially equal to provide legs that can be placed on a surface tostabilize the rebar chairs.
 22. A weld-less rebar chair comprising anelongate rod arranged along a predetermined direction and defining anaxis, said rod being formed into at least a plurality of loops extendingsubstantially equal distances in a direction normal to saidpredetermined direction spaced from each other along said predetermineddirection, alternate loops being angularly offset relative to a planepassing through said axis and each forming angles with said plane lessthan 90°.
 23. A method of producing a weld-less rebar chair comprisingthe steps of selecting a length of an elongate continuous rod andarranging it along a predetermined direction and defining an axis;bending said rod to create at least a plurality of loops extendingsubstantially equal distances in a direction normal to saidpredetermined direction spaced from each other along said predetermineddirection; and angularly offsetting alternate loops about said axis toopposite sides of a plane passing through said axis and each formingangles with said plane less than 90°.